﻿//  Copyright 2016 Google Inc. All Rights Reserved.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.

using System;

namespace NtApiDotNet
{
    /// <summary>
    /// Disposable class to scope an impersonation context.
    /// </summary>
    public sealed class ThreadImpersonationContext : IDisposable
    {
        private readonly NtThread _thread;
        private readonly bool _container;

        internal ThreadImpersonationContext(bool container)
        {
            _container = container;
        }

        internal ThreadImpersonationContext(NtThread thread) 
            : this(false)
        {
            _thread = thread;
        }

        /// <summary>
        /// Revert impersonation back to the current user.
        /// </summary>
        public void Revert()
        {
            if (_container)
            {
                NtThread.DetachContainer(false);
            }
            else if (!_thread.Handle.IsClosed)
            {
                using (_thread)
                {
                    _thread.SetImpersonationToken(null, false);
                }
            }
        }

        void IDisposable.Dispose()
        {
            Revert();
        }
    }
}
